Each of the Betamax and VHS videocassettes has a pair of tape spools loosely positioned side-by-side within the cassette housing. When the cassette is inserted into a videotape recorder, a pair of spindles fit into interior teeth of the hubs of the spools and press the spools against a spring which is mounted in the cassette. The spring has two arms, each of which contacts a wear button on one of the tape spools.
The tape spool of a typical Betamax or VHS videocassette has two parts, each a single piece of plastic. The first piece includes a hub, one flange, and a wear button at the end of the hub opposite its flange. The second piece is a transparent plastic disk which provides the other flange and has a central opening through which the wear button protrudes. Typically the two pieces are ultrasonically welded together. Because the first piece includes the wear button, it must be molded of a plastic which is wear resistant and hence relatively expensive.
The compact VHS-C videocassette also has two tape spools, one of which is similar to the spools of the full-size VHS and is typically constructed in the same way.
After magnetic recording tape is wound into an assembled videocassette, visual inspection sometimes reveals a scratched transparent flange. When ultrasonically welded, the spool and wound tape would be discarded, because it would be impossible to replace only the scratched flange. U.S. Pat. No. 4,289,282 shows a videocassette tape spool which would permit a scratched transparent flange to be replaced.